Apparatus to deliver breathable gas to a patient typically include a flow generator, an air delivery conduit, and a patient interface, wherein the air delivery conduit delivers pressurized air from the flow generator to the patient interface in contact with the patient's face. Throughout a range of air delivery systems, from both simple CPAP systems to more complex non-invasive positive pressure ventilation (NIPPV), there is frequently a need for communication between the patient interface and the flow generator, other than through the air delivery conduit. This communication thus requires a second conduit routed from the flow generator to the patient interface.
One example of this requirement is the measurement of pressure. The pressure delivered to the entrance of the patient's airways is generally estimated by measuring the pressure at the flow generator and applying a correction factor in accordance with the known characteristics of the relevant conduit and patient interface. The pressure delivered to the entrance of the patient's airways can also be measured directly in the patient interface. In this case, a pressure transducer may be mounted on or near the patient interface and in communication with the interior of the patient interface by way of a port or linking sensing tube. Alternatively, the sensing tube is connected between an appropriate port on the patient interface and a pressure transducer located remotely from the patient interface such as in the flow generator housing. An example of this type of system is the SULLIVAN® Constant CPAP manufactured by ResMed Ltd, Australia, which uses 3 mm-diameter tubing.
A further example of where a separate communication tube may be required is where sampling of the gas is required, for oxygen or carbon dioxide monitoring for example. Alternatively, the supply of oxygen or any drug delivery system may require a separate tube communication system between the flow generator or any remote location within the hose system and the patient interface.
When these pressure sensing or air delivery tubes are a separate component to the main air delivery conduit, the sensing tube can become tangled or occluded if bent. The sensing tubes above are also cumbersome to handle and assemble by the user. In an attempt to address some of these disadvantages, systems have secured the sensing tube and the gas conduit together with clips or the like to form a tubing assembly. However this approach requires additional components and can be cumbersome and difficult to assemble. An alternative approach is to incorporate the additional communication system (e.g., sensing tube) with the air delivery conduit such as the system described within DE19954724 to Bernd. One embodiment shows a spiral tube incorporated around the exterior of the air delivery conduit. A range of respiratory conduits are shown within WO 03/026721 A2 to Schein, that incorporate tubes within the respiratory conduit.
Any of the systems described above that connect an additional communication system or auxiliary tube between the patient interface and the flow generator or other device at a distance along the air delivery conduit requires a connection system between the components. This connection may occur between the patient interface and the air delivery conduit, the air delivery conduit and the flow generator, or the air delivery conduit and intermediate components such as humidifiers. This connection mechanism should ideally be easy to assemble, non-directional, secure, lightweight and easy to clean.
An example of an existing connector system is shown in DE19954724, which may be used with MAP components such as the MAP MiniMax humidifier. As shown in FIG. 5 of DE19954724 (See FIG. 19 of the current application), one of the connections requires connection of a port incorporated within the cuff that requires alignment with the patient interface or connection device. As shown in FIG. 6 of DE19954724. (See FIG. 20 of the current application), another one of the connections requires connection of an external tube with both the patient interface and a port on the air delivery conduit cuff. This solution requires dexterity by the patient in the correct assembly and alignment of the components.